Diversified types of liquid sprayers are currently used in a variety of fields, including the fire-fighting equipment, as fire-extinguishant sprayers.
As an example, the U.S. Pat. No 5,125,582 (IPC B05B 1/00, published 30.06.1992) discloses the construction of a liquid sprayer designed for the generation of cavitation liquid flows. The prior art comprises a casing with a flow-through channel formed by a nozzle and a cylindrical chamber. The nozzle is made in the form of a converging tube communicated with a conical diffuser without continuous joining of their surfaces. A length of the cylindrical chamber is at least three diameters of a minimal section of the nozzle. On supplying the liquid under pressure into the inlet opening of the converging tube of the nozzle, the liquid flow section is contracted and the outflow velocity is increased. An abrupt expansion of the liquid flow in the diffuser results in liquid cavitation. The liquid cavitation is intensified in the process of passage of the liquid jet through the cylindrical chamber, where the liquid jet is expanded and return vortex flows are generated. An annular vacuum zone is formed around a conical jet to initiate a cavitation process and an associated liquid flow dispersion process.
However, despite the possibility of an intensified cavitation process, the prior art liquid sprayer does not provide for the formation of a steady-state fine-dispersed liquid flow, that can retain its shape and section size at the distances of up to 10 m, which is of particular importance when the sprayer is employed for suppressing the sources of fire.
A vacuum-type sprayer head (the author's certificate, USSR, No 994022, IPC B05B 1/00, published 07.02.1983) is also known, which comprises a nozzle composed of a converging tube and a cylindrical head located coaxial with the nozzle. The cylindrical head is equipped with ejection holes formed at the side of its outlet opening to admit atmospheric air into a vacuum zone in the cylindrical head cavity. As a result the incoming air saturates the moving liquid flow to provide for splitting of the flow into small droplets.
Russian Patent No 2123871 (IPC A62C 31/02, published 27.12.1998) describes a head for forming an aerosol-type water spray, which allows the dispersion of a gas-drop jet to be improved. The prior art sprayer (head) comprises a casing having a flow-through channel formed as a Laval nozzle, an inlet pipe union for supplying liquid under pressure, and a distributing grid located between the pipe union and an inlet section of the Laval nozzle. The sizes of the distributing grid holes are 0.3÷1.0 the diameter of the Laval nozzle critical section. While passing through the holes of the distributing grid, the liquid flow is split into separate streams, which are sequentially concentrated in the nozzle orifice and accelerated to high velocities. Such embodiment provides for a sufficient distance of discharging a fire extinguishant and fine spraying.
The closest analog for the claimed versions of the sprayer is a liquid spraying device described in the Patent DDR No. 233490 (IPC A62C 1/00, published 05.03.1986), which is adapted for feeding a fire-extinguishant to a source of fire. The device is composed of a casing involving a flow-through channel, into which a working fluid, including water, is supplied under pressure. The flow-through channel of the device is composed of an inlet portion formed as a converging tube, a cylindrical portion and an outlet portion formed as a conical diffuser, said portions being sequentially joined with one another in axially aligned relationship. Also, the device comprises a reservoir containing a fire-extinguishant, which is communicated with the diffuser via radial passages.
During operation of said device the liquid (water) is supplied under the pressure of 1.5–2.0 bar into the inlet opening of the flow-through channel and is sequentially accelerated in a nozzle formed by the converging tube, the cylindrical portion and the diffuser. The fire-extinguishant is ejected into the diffuser through the radial passages to be further intermixed with the liquid flow. The implementation of said device allows the reach of the fire-extinguishant to be essentially increased to thereby improve the fire-fighting effectiveness, when know extinguishants are utilized. However, the given embodiment does not provide for the generation of high-velocity fine-dispersed gas-drop jets. The liquid flow is used in such devices for the most part as a carrier for an additionally introduced fire-extinguishant, for example, for foam-generating additives.